Switching the type of redox activity of colloidal nanoceria by Re3+ (Re = Y, Eu, Tb) doping

Highlights: • Surface structure determines the type of redox activity of nanoceria. • Nanoceria decomposes hydrogen peroxide without generation of hydroxyl radicals. • Presence of Ce³⁺-V_o-Ce³⁺ surface complexes provides nanoceria by enzyme-like action. • Ce³⁺-V_o-Re³⁺ complexes (Re = Y, Eu) provide Fenton-like HP decomposition. • Kinetics of HP decomposition by nanoceria is similar to kinetics of enzyme action. Nanoceria (CeO_2-x) is well-known for its enzyme-like antioxidant activity determined by Ce³⁺↔Ce⁴⁺ redox cycles on the surface of nanoparticle during interaction with reactive oxygen species. We show the crucial role of the surface defect structure in the mechanisms of interaction of Re³⁺ (Re = Y, Eu, Tb) - doped nanoceria with hydrogen peroxide (HP) and hydroxyl radicals (^• OH). Both catalase-like (for CeO₂:Tb³⁺) and Fenton-like (for CeO₂:Y³⁺ and CeO₂:Eu³⁺) HP decomposition was observed for Re³⁺-doped ceria nanoparticles leading to antioxidant or prooxidant activity, respectively. Overall, the type of Re³⁺ ion determines the mechanism and efficiency of redox activity of nanoceria.